Twice now I have been attacked by another player who, when I was about to deal a finishing blow, logged off. I was a little frustrated that my attacker had an "easy way out". I think there should be a another consequence for attacking attacking another player. If you attack, or fight, another player there should be a timer that starts that prevents you from logging out, maybe for a minute or so. This might make some players think twice about attacking another since they won't be able to escape as easily.
Of course, there are ways to circumvent this. Like shutting down the client abnormally. To deal with this the player's character could be forced to stay logged in for 1 minute even if the client is shut down, thus they give up control of their character.
Whether or not the retaliator should be able to log out immediately, I don't know. Should he/she be free from the consequence for defendending one's self? Or should they suffer the same result?